In recent years, organic devices using an organic compound in place of an inorganic material as a functional material are developed and are getting attention. The organic device is able to make an instrument as flexible as the instrument using the inorganic material is difficult to do so. Further, a significant weight saving of the instrument is made possible by the organic device. Further, the organic compound is easy to modify its chemical structure and to change a synthetic method. As a result, there is a lot of freedom in designing, whereby the possibilities for enhancement of production efficiency and reduction of production cost in mass production as well as improvement of material property are widely expanded. Taking these advantages, development of organic devices as a next generation device is actively moving forward, focusing on potable instruments, image-involved instruments or the like. Typical examples of the instruments include an organic electroluminescent element, an organic photoelectric conversion element, an organic transistor, a touch panel, and an electrophotography.
In the organic devices, a charge transporting material is used as a functional material for controlling their electrical or chemical behavior. With respect to the charge transporting material, a productive aptitude at the time when the charge transporting material is prepared or incorporated in the device is required in addition to basic properties such as charge transportation property and photostability. Further, a mechanical strength directly linked with durability at the time of use is also needed.
As a method of forming a thin film of organic material involved in the production of the organic device, a vacuum deposition method, a wet coating method and the like are proposed. However, the vacuum deposition method needs a large-scale machine. In contrast, the wet coating method can be carried out using simple equipments. Moreover, making of large area can be easily done by the wet coating method. For these reasons, the wet coating method is favorable from the viewpoint that a productive efficiency can be enhanced with a reduced cost, so that the wet coating method is a production method suitable for industrial-scale production. Accordingly, the charge transporting material is also desired to have a productive aptitude in the wet coating method. Specifically, a film is produced by coating a coating solution in which an charge transporting material including an organic material as a component is dissolved in a solvent, followed by removing the solvent. In the preparation of the coating solution, solubility of the charge transporting material with respect to the solvent is needed. Therefore, a technique in which various kinds of substituents are introduced into an organic compound that constitutes the charge transporting material is used (see Patent Literature 1).
Further, in order to enhance strength of the produced organic device, the Patent Literature 1 proposes to enhance a mechanical strength by the method of introducing a crosslinking group into an organic compound that constitutes the charge transporting material, and forming a coating film of this compound, followed by curing. As for the crosslinking group, an acrylic group and a methacrylic group are excellent in terms of crosslinking property and handleability. As a technique for introducing an acrylic group or a methacrylic group, a production method in which an acrylic acid or an acrylic acid halide and an alcohol product of a compound that constitutes an charge transporting material are subjected to condensation is a common method.